I know how to search for a single string in several files at once with Sublime 3 (explained here).
What I need to do is to search for multiple strings>
I tried this on Sublime Text2, so should work on Sublime Text3 as well.
Field: string1 string2 string3 string4 Where: /path_to_folder_containing_the_files_I_want_to_ search/
Note: uncheck '.*' which means Regular Expression and check "" which means look for the whole word.
This will search for the pattern "string1 string2 string3 string4" in all the files in the mentioned folder.