Question about my 2007 Mercedes Benz E350

So I have a 2007 Mercedes-Benz E350 with over 249,000 miles. When I hit the gas, there's a ticking noise I'm assuming from the engine, but the noise goes away after taking your foot off the gas pedal. Also, when I remove the oil cap, there's a little bit of smoke with oil coming out a little when the car is on. Thank you!