If you add a second word to the search, the items that contain both search terms should rise to the top of the search results (similar to a Google search). For example, if you type the following, then the instagram account for the client named “Clientname” should be at the top of the search results:
insta clientname
You can also use advanced search options, such as making the presence of one ore more search terms mandatory (in the examples below, the > character prefix is required at the start of the search string):
>+*insta* +clientname
or even some variation of the following (if you are still getting false positives):
>+login.uris:*insta* +login.username:clientname
If you provide more information about your scenario, I can help put together a search strategy that should work.