‘Silence’ spell cast on a PC or object?

A PC Cleric wants to cast a ‘Silence’ on one of the two PC Fighters in their party so that the Fighters can enter a room to kill orcs without having the noise of the battle alarm orcs in other rooms. As long as the Cleric concentrates on the spell and doesn’t engage in other activities to stop the concentration is this ok? What about casting it on an object that you move around or throw into the midst of a room to eliminate the noise from activity/battle?