title: How to find fields that contains one of array elements?
body: <p>It's easy for find fields that contain an string like this:</p>
  
  <pre><code>db.users.findOne({"username" : {$regex : ".*son.*"}});
  </code></pre>
  
  <p>I want to know if there is a way to check all array elements this way?
  for example something like this:</p>
  
  <pre><code>s = ['one', 'two', 'three']
  db.users.findOne({"username" : {$regex : ".*s.*"}});
  </code></pre>