But if there is an uncaught exception in my app, it should be everywhere not only in one device.
You would hope so. but in practice that turns out not to be the case. If the app crashes there *will* be something in the logcat.
And how can i tell my client to give me logs as it doesn't crashes on my side.
Talk to him/her? Or, if the app is distributed via the Google Play Store, you would find it in your developer account there.