title: Searching multiple fields in mongodb
body: <p>I have a mongo collection. Now a user can search using any field or all of the fields based on his needs. </p>
  
  <p>For example :- A user can search using any one of attribute or any two attribute or any number of attribute he remembers of the fields present in the collection. Help me to decide which operator or combination of operators should I use?</p>
  
  <pre><code>{"_id":1, "field1":"hi","field2":"bye","field3":"bro", "field4":"stuff"},
  {"_id":2, "field1": "hello", "field2": "back", "field3": "fat", "field4":"cat"},
  {"_id":3, "field1": "some", "random": "foo", "stuff": "bar", "field4":"help"}
  </code></pre>