@ Mithun
Please mention the ascendant and why wud you want to wear rahu, ketu and Shani.
You already have the nine planets in your horoscope, why wear them too? It would be the same thing.
In my opinion, never wear gem stones as a general remedy for averting evil. It does not work that way. Let me ask you a question. Do you daily take meds to avoid illness, irrespective of whether you have the illness now? One takes meds only when one is sick. The same applies to gem stones. Wearing them without a specific need will take you everywhere other than happiness, success and satisfaction.
Wishing you good luck, may God bless you and over all
CHEERS