My b was having the same case as u. He ate only white rice and bread for more than a month.
A nurse in the health center suggested cook a very very little (say, just a tea spoon) minced meat with the rice, and let him get used to the taste/texture of meat. After he get used to it, we can add in some more meat gradually or add in some other kind of veg. Better start with fish or chicken as they are white in color, same as the rice. He would not refuse in the first sight of it.
I try this to my b, and it works. But u have to be patient and do things gradually. Now my b eat much better, although he still reject some foods, his diet included rice/noddle/bread, meat & veg/fruit.