We define a modified covariant Klein-Gordon (KG) equation containing quantum vacuum contributions arising from the self-interaction of matter with its own internal kinetic energy. The modified KG equation is exemplified for a variety of vacuum fields and various properties of the equation are articulated thereof. Generalized commutation and Energy-Momentum relations are characterized for a null vacuum-phase scenario of the proposed vacuum field $lambda$. Within this limited scenario, a representation theorem is introduced suggesting that one can equally modify the spacetime structure or momentum operator in articulating the proposed quantum theory. Such a modified KG equation is further shown to eliminate infrared and the ultraviolet divergences in the generalized Klein-Gordon propagator.