Ok, here is a description of the noise.
It is some kind of a repetitive mild clapping or tapping that can for sure be associated to a rotating part. To my experience, it does not sound like a valve clapping or engine pinging. The noise happens when I start the car and when I put the trans. in D or R. There is no noise when I increase the rpm and in neutral. When I brake, it reduces a little. When I accelerate, the noise frequency and intensity increase as well.
It comes from the front for sure. One guy suggested that it was caused by a faulty accessory belt tensioner pulley or idler pulley... My dealer says that a timing belt cannot be loose and making such a noise.
This is the best description I can give...