practical use of homomorphic encryption Are RSA and Elgamal partially homomorphic techniques? which one is better if one want to use it for practical purpose? and is there some FHE technique which can be used practically?
Yes ElGamal and RSA (without padding) are both partially homomorphic (wrt. mulitiplication). I can not think of any applications that uses the homomorphic properties of these schemes in practice. However, in terms of efficiency they are probably about equal. Evaluating the homomorphism involves just one multiplication for RSA and two for ElGamal. As for security, ElGamal is the way to go. ElGamal at least provides semantic security which unpadded RSA does not. 

Wrt. FHE: the known constructions of FHE are still quite computationally heavy. However, since the first construction in 2009 a lot has happened to make FHE more efficient. At this point it is conceivable to run FHE in practice although it would be very very slow. In this paper
researches evaluated the AES circuit using FHE for example. Whether or not it would be practical to use for any given application of course heavily depends on the application.