Create a dynamic saved search which treats user input as parameter?

Hi,

I have searched and found many similar topics on this forum, but I can't seem to find something that clearly phrases/addresses what we want to do.

Is there a way to use a formula field (or something else) to directly reference the search text input?  For example, we want to have dynamic criteria for "message contains (user input) OR subject contains (user input) OR (user input.length > X)" etc etc.

Filters do not seem to help because we are talking about referencing the search text itself as a parameter/variable.  We don't want people to have to specify 10 different filters manually each time they search.  I know the API allows for searches, but how does this help in terms of USERS being able to type into a box and search?  Do I have to write code to perform the search in the API and then reconstruct the entire search results page as a suitelet?