Hi Vijaysahay, I can understand your feeling. I used to be the same when I  got my bike. But realized it was getting insanity and possessive about the bike.  About the maintenance of the bike. Water from above is pretty clean and  harmless. It’s the oil/grit/rubber emulsion from the road that gums up your  bike. Fenders will protect you and the bike from this muck, and avoid that  charming brown stripe on your lower back. A helmet peak will keep rain of your  glasses. In warm rain, its best to get wet.
In cool rain, wear a waterproof,  but you have to modulate your work-rate so as not to sweat. In cold rain add  rain pants, you need to pay special attention to your feet, either neoprene over  boots, gortex under-socks, or more sensible, keep the darned water out in the  first place with waterproof boots.
Wear bright colors, lights if necessary,  keep your rims dry with braking, and maintain extra stopping distance