I'm not sure your signal will improve by putting several mic's close together. It creates signals which are out-of-phase with one another. High frequencies will be blurred. (The 'S' sound is mainly in the high frequencies.)
I would set up single microphones, 10 or 20 feet apart, and run them all into a mixer. A simple op amp mixer might do the job. Or possibly you'll need to amplify each mic separately, then send its signal to a unity gain mixer.
For speech recognition to succeed, the mic should be close to the mouth. If it is several feet away, we must pronounce words clearly and slowly.