I have had this question for a long time:
Will a batsman be given out if the ball hits the pad or a helmet of a wicket keeper and the catch is taken by another fielder?
When this question was asked in 2012, the batsman will not be given out if the ball hits the bat and then the helmet of the wicket keeper or any other fielder before the catch is taken. But pads are similar to gloves for a keeper; hence if the ball hits the bat and then hits the pad and then is caught by a fielder, the batsman is out.
However, the 2017 update to the Laws meant that catches can be taken after the ball hits a fielder's helmet; quoting from the MCC's summary of the changes:
A change has been made so that the ball can be caught after it strikes a helmet which is being worn by a fielder or the wicket-keeper
Providing of course that the batsman's bat has made contact with the ball before reaching the wicketkeeper or other fielder then yes, the batsman will be given out as long as the ball doesn't hit the floor.
As per new ICC Rule amendment (Sept 26th, 2017) Catch taken after hitting helmet of the fielder is a fair catch.