For sure. That's all documented here:
https://tiddlywiki.com/#search%20Operator
I much prefer the "wide open" (search all fields), so that if I can catch the tiddler I want by a selection of words I remember being wherever they happen to exist in the tiddler, so maybe a word from the title, a word from some custom field, a word from the text.
You could make the "field list" for search operator come from another edit text widget, so you have the flexibility of dynamically specifying which field(s) you want to search.