There are really two answers to your question. The first is that your RAID controller must support drives larger than 2.2TB in order to use the 4TB drives.
If your equipment supports 4TB drives, you will be able to create an array size that is equal to 3 drives if you use four in RAID 5, the equivalent of one entire drive is used for the striping to provide single drive redundancy.
Take a look at RAID 5 at THIS PAGE
to see a graphic representation of how the parity stripe (which allows data retention if one disk is lost) is spread over 4 drives -- ignore the drive marked hot spare at that does not apply for you.