Search users by applying filter

Suppose I did conversation with 5 members. 

1. Username - Deepanshu

2. Username - Eresh

3. Username - Shiva

4. Username - Prince

5. Username - Deepak

If the user retrieves conversations without applying any search filters, they will get all 5 conversations.

If the I as user wants to applies a search to find user  where the search keywords is "dee," then I want to see the result with 2 conversations—one with Deepanshu and the other with Deepak.