As others have said, it's not unusual at all for a 16-yr-old not to know what he wants to study or where he wants to go to college. My older son has changed his career/major choice twice from the age of 16 to his current age of 19, and the college he now very happily attends and plays baseball at was about #5 on his list when he started thinking of colleges at age 16. (On the other hand, my younger son chose his intended career in THIRD GRADE and has not wavered from it, and we do not believe he will change his mind.)
One thing our oldest did at about age 16 was to fill out a couple of informal "interest assessments" - rating on a scale of 1 to 5 statements like "I like to do puzzles", "I like to influence or persuade people", "I like to act in plays", etc. It was an easy and interesting form to fill out, and the answers to a bunch of those statements showed a pattern, which then was matched up to a list of maybe 50 different jobs that were typically a good fit for someone with that combination of interests. The assessment that was most helpful to my son was at
http://www.mncareers.org/start_exploring.asp?pageid=se02 . This site was specific to us here in Minnesota, and my son received a related book at "college night" at his HS, which listed colleges in Minnesota and surrounding states that offered majors/degrees needed for those careers. Perhaps you could find a similar college list for your region, or the region where your son might wish to attend college, but the interest survey would apply to any region.
I'm not suggesting that your son has to get everything figured out at age 16, but the tools above helped my son to begin a decision process that evolved over a couple of years, and is still evolving.