Search custom field by =>

Hi, I have a custom field Quantity and I want to search by >= …. not = … or ignore it.

I mine: User have to see a “Quantity” field in search form but this value will be ignored in search and used with a js script after first search load to mark as valid or not each search result.

The same with a date field. It will be used for preferible booking but It will not filter results. It will help to mark as Available or not the search result in the search results page after first loading.
In this case with the Date field: There is any known way to filter available date?

Im sure this is a easy question about edit search logic or add dummy fields in html… but i can figure it out now…

Important!
If you have a link to direct me to modify/filter search/search results… so i can “mark” as valid the result set before first load will be great too so I will be able to use WPGD load logic without my js…

The main objective is to filter by location the main results and just “Mark as valid”… or “not valid” the results depending on less important search fields to avoid Empty results,… and apply a different css classes.