Document Search

Searching for client documents. If I want to find a specific document for a client, we could have multiple folders on the client record, plus case folders to look through. We need a way to search them. So either a search function at client level, or an enhancement to the main search bar. I've tried searching for the clients surname and one word from the document name, but it only shows me documents with the client's surname in and ignores the second word in the search bar. Do I need to use "" or something?