Clicking bearings are a fairly regular and normal occurrence, especially with the drive wheels. There are several solutions to remedy clicking bearings. Often the axle nut is too tight and will cause one or more bearings to click.
Using a skate tool, tighten the nut until it is tight and then back it off a quarter turn or so until the clicking stops but there is no lateral movement of the wheel. Another remedy is to use a little white lithium grease on the bearing seats (where the bearing rests in the wheel).
It is advisable to clean your bearings or replace them regularly. Especially if they have been exposed to water, sand, or excessive dirt and dust.