Calibre has 2 forms of library search results.
1) is the Highlight
2)Display only resurts.
This is controlled by the setting in Preferences: Searching: (second item)
the third item puts the toggle onto the toolbar for those that want to switch frequently.
IMHO mode 2 is better if you just use a fragment of the full value (and have quite a few books that might satisfy the term
Note the What to search by default Box
If you do not specify what to search (eg authors:smith), calibre will look in every possible column. This limits where to look