Elasticsearch get keywords

Question

i'm trying to find all the keywords in an index. This is for doing an auto complete on a word while typing.

but how would you set up that filter? or do I need to map this with the index?

note: I don't want to autocomplete on a file full result name (so If I store that big brown fox is dead) the results could be big, brown, fox and dead)

and the more of for example I have the word fox being indexed, the higher it's score is

I have a full autocomplete on the whole word while you type (so this isn't what i'm looking for):

This would give me that big brown fox is dead when I type fo. instead of only fox

  var c = new ElasticClient();
  var results = c.Search<dm_document>(s => s
      .From(from)
      .Size(size)
      .Index("testindex")
      .Query(q => q.Term(d => d.object_name.Suffix("autocomplete"), search))
  );
  return results.Documents.Select(d => new { d.object_name, d.r_object_id }).ToList();

with the following index setup

  var createResult = client.CreateIndex("testindex", index => index
      .Analysis(analysis => analysis
          .Analyzers(a => a
              .Add(
                  "autocomplete",
                  new Nest.CustomAnalyzer() {
                    Tokenizer = "edgeNGram",
                    Filter = new string[] { "lowercase" }
                  }
              )
          )
          .Tokenizers(t => t
              .Add(
                  "edgeNGram",
                  new Nest.EdgeNGramTokenizer() {
                    MinGram = 1,
                    MaxGram = 20
                  }
              )
          )
      )
      .AddMapping<dm_document>(tmd => tmd
          .Properties(props => props
              .MultiField(p => p
                  .Name(t => t.object_name)
                  .Fields(tf => tf
                      .String(s => s
                          .Name(t => t.object_name)
                          .Index(Nest.FieldIndexOption.NotAnalyzed)
                      )
                      .String(s => s
                          .Name(t => t.object_name.Suffix("autocomplete"))
                          .Index(Nest.FieldIndexOption.Analyzed)
                          .IndexAnalyzer("autocomplete")
                      )
                      .String(s => s
                          .Name(t => t.title)
                          .Index(Nest.FieldIndexOption.NotAnalyzed)
                      )
                      .String(s => s
                          .Name(t => t.title.Suffix("autocomplete"))
                          .Index(Nest.FieldIndexOption.Analyzed)
                          .IndexAnalyzer("autocomplete")
                      )
                      .String(s => s
                          .Name(t => t.text)
                          .Index(Nest.FieldIndexOption.Analyzed)
                          .IndexAnalyzer("snowball")
                      )
                      .String(s => s
                          .IndexName("tag")
                          .Name("keywords_test")
                          .IndexAnalyzer("keywords")
                      )
                  )
              )
          )
      )
  );

but this results in the full name of the objects, I want only the keywords

Update: Found out how to get the terms, not sure if this result is what I need, but it's giving me already terms

POST _search
{
    "query" : { "query_string" : {"query" : "*"} },
    "facets": {
       "tags": {
          "terms": {
             "field": "title"
          }
       }
    }
}

Now I need to figure out on how to search on those terms