title: MongoDB find() with dot notation does not work
body: <p>I am creating a search function in my app that searches through: title, description and product manufacturers name. So far, searching with title or description <strong>works</strong> fine but it does not work when I try manufacturers name (in fact, it is the only one that uses dot notation in querying)</p>
  
  <p>I have some data in DB:</p>
  
  <pre><code>title: 'GLT 488',
  description: 'an item',
  Manufacturer:
      { _id: 5ababaa8d1c9c006c8fd8975,
      key: 'audio-note',
      name: 'Audio Note',
      },
  </code></pre>
  
  <p>This is how I am using MongoDB's find function:</p>
  
  <pre><code>const regex = new RegExp(escapeRegex(req.query.search), 'gi');
  q.find({
      $or: [
          {'title': regex},
          {'description': regex},
          {'Manufacturer.name': regex}
      ]
  },
  </code></pre>