title: Mongo C# driver - Contains Filter
body: <p>I am using the latest version of Mongo C# driver which uses a lot of Async and builder pattern. Which is nice. I am trying to convert SQL where clauses into Mongo FilterDefinition object. </p>
  
  <p>Any idea how to handle "contains"?<br>
  like:</p>
  
  <pre><code>where x contains 'ABC'
  </code></pre>