In general I only use the OData client from JavaScript. When using .NET, I use the SDK libraries that provide authentication and access via the CrmServiceClient class.
To use the OData client from C#, this article outlines the various authentication methods: https://msdn.microsoft.com/en-us/library/mt595798.aspx
Web API authentication patterns
There are three different ways to manage authentication when using the
Web API. With JavaScript in web resources
When you use the Web API with JavaScript within HTML web resources,
form scripts, or ribbon commands you don’t need to include any code
for authentication. In each of these cases the user is already
authenticated by the application and authentication is managed by the
application. With on-premises deployments
When you use the Web API for on-premises deployments you must include
the user’s network credentials. The following example is a C# function
that will return an HttpClient configured for a given user’s network
credentials: C#
private HttpClient getNewHttpClient(string userName,string
password,string domainName, string webAPIBaseAddress) {
HttpClient client = new HttpClient(new HttpClientHandler() { Credentials = new NetworkCredential(userName, password, domainName)
});
client.BaseAddress = new Uri(webAPIBaseAddress);
client.Timeout = new TimeSpan(0, 2, 0);
return client;
}
With Microsoft Dynamics 365 (online) or internet facing deployments
When you use the Web API for Dynamics 365 (online) or an on-premises
Internet-facing deployment (IFD) you must use OAuth as described in
Connect to Microsoft Dynamics 365 web services using OAuth.
If you’re creating a single page application (SPA) using JavaScript
you can use the adal.js library as described in Use OAuth with
Cross-Origin Resource Sharing to connect a Single Page Application to
Microsoft Dynamics 365.