If it was a desktop Mac, you would have a designated key for what you are describing, but since space is limited on a notebook, Apple has done this for space saving purposes.
I use a wireless keyboard with my MB that allows me to do what you are wanting and is made for Mac. It is an S530 by Logitech.
Otherwise, I don't know if there is a way to change it to what you want in keyboard setup in System Preferences, but you are welcome to check into it and let the rest of us know what you get.
Good Luck.
Adam