Write a simple node.s controller example

I have started a small project on node.js with MongoDB and have implemented some routes and controllers, but i am having problems with one controller that is used to do a search on attributes. The Controllers to be implemneted is a GET and can contain or not a query localhost:3000/documents? My documets contains 3 attributes (2 arrays of string and string), and i need to check if the atribute contains a certain word . The query can look up on one atribute (for exemple only name) or on and all 3. If the query is not present, it should return just all the documents. I have attached the sample of my code, and a small sample of JSON for documnt.