Convert WebRequest to RestSharp

Question

I'm trying to use RestSharp but I'm having some difficulties converting my old code. Here is a little snippet:

System.Net.WebRequest request = WebRequest.Create("http://192.168.20.42/otrs/nph-genericinterface.pl/Webservice/GenericTicketConnectorREST/TicketUpdate/22");

    request.ContentType = "application/json";
    request.Method = "PATCH";
    byte[] buffer = Encoding.GetEncoding("UTF-8").GetBytes("{\"UserLogin\":\"user\", \"Password\":\"pass\", \"Ticket\":{\"QueueID\":\"2\"}}");
    string result = System.Convert.ToBase64String(buffer);
    Stream reqstr = request.GetRequestStream();
    reqstr.Write(buffer, 0, buffer.Length);
    reqstr.Close();

WebResponse response = request.GetResponse();

How would I convert this to RestSharp?

thank you all.