Hi!
I believe the only possible way is to either modify the search code, or use one of the filters. I can’t really think of an easy solution, I’m sorry.
You can take a look at some examples in the knowledge base how to parse and modify the results, for example: https://wp-dreams.com/knowledge-base/numbering-the-results/
In that example you have access to the post ID as well with the
[code]$results[$k]->id[/code]
variable in the foreach loop.
Then if you know the post ID, you can use wordpress core functions the get custom fields and so on.