Recursive Search for part of filename

Question

Hello, I want to be able to search for a file in a directory I have selected by only part of the filename. For example searching the term "sharp" would get me the files csharp.txt and sharp_sword.jpg etc. I already have a recursive search which just finds all the files of a specific extension, but I am not sure how to do it with part of a filename.

Will provide part of my code if it is needed, I am sure theres a simple fix.