We have configured the admin/editor GUI to use EPiServer search. It works but some search results seem off. 

For example I'm searching using the media tab in the GUI for the file "company-logo.jpg".

Search phrase: company 
Returns image: yes

Search phrase: company-
Returns image: yes

Search phrase: company-l
Returns image: no

...

Search phrase: company-logo
Returns image: no

Search phrase: company logo
Returns image: no

Search phrase: company-logo.jpg
Returns image: yes

I don't get why searches for "company-logo" or "company logo" don't return the image?