Hello stmoong.
It is no big deal to clean camera optics and sensor. I have done it on all my lenses and camera bodies.
You described that you saw finger print smudges on the lens. It can be very easily cleaned.
If you are hands on type, you can DIY. If you are in doubt please let the professionals clean it.
Find a work area that's dust free.
You will need to get hold of these few essential items:
1) A blower (rocket blower)
2) A lens cleaning fluid. (Visible dust lens clean)
3) A micro fibre wiper (Visible dust magic cleaner)
Best to wash your hands with a mild soap before you start. If you have clean room gloves please wear them. If not washed hands are fine.
Use the blower to blow away any loose dust or dust from the lens optic.
Remove the wiper from the packing and handle it very carefully. Do not place it on the table anywhere it is dusty or dirty. If you drop it on the floor, you will need to throw it away and get a new one. After cleaning, please store the wiper in a clean and dust free container.
Fold the micro fibre wiper without touching the part that you are going to use for wiping the optic. Spray a small amount of cleaning fluid on it. Gently place the folded tip of the wet wiper on the optic centre and wipe gently in a circular motion to the sides. Do not wipe back and forth and do not reuse the same area of the wiper to clean again.
If the finger prints are still there, repeat the cleaning process but this time wet the wiper a little more and place the wiper on the smudge for a few seconds and wipe from there.
Finger prints and smudges are the hardest to remove especially if it is an old print. Finger prints / smudges contains oil and acid.
As for the sensor, I doubt it is so dirty that you can see streaks. Probably what you saw were just the reflections or interference patterns as the ambient light falls on to it.
Just mount the lens and shoot at a white paper with a small aperture. Review the shot of the white paper, zoom in and see if you there are streaks or spots. If you see streaks or spots, then you definitely have dirt on the sensor.
You can try blowing the dirt away from the sensor with the blower, hold the camera with the sensor facing downwards and point the blower upwards near the sensor and give it a few puffs. Never let the blower tip touch the sensor.
Repeat the white paper shot again. If the streaks or dirt are gone, you are done. If they still remains, then the sensor will need a dry or wet clean.
For dry or wet sensor cleaning please take it back to Olympus if aren't game enough for it. I don't want you to bust the camera sensor.
If you think you are game enough to clean the sensor, then you will need to get the u4/3 sensor wiper from Visible dust. Please follow the instructions exactly on the product.
You can get all your cleaning supplies I mentioned from Cathay Photo at Peninsula Plaza and at Marina Square.