Effective Strategies for Conducting a Company Key Contact Search

Hi guys, I'm wanting to do a super specific Key contact search from a company and was wondering what the best way to go about it is. The "Find Contacts at Company" is doing an okay job but it is missing people out and I have no clue as to why. i have loads of key words I need to search for but this needs to be a profile wide search not just the job title. some of these companies are ~10,000 employees so needs to be as filtered as possible. Any help would be really appreciated.