  We characterize experimentally and theoretically the high-energy dielectric
screening properties of the prototypical correlated metal SrVO$_3$. The
dynamical structure factor measured by inelastic x-ray scattering spectroscopy
as a function of momentum transfer is in very good agreement with
first-principles calculations in the adiabatic local density approximation to
time-dependent density-functional theory. Our results reveal the crucial
importance of crystal local fields in the charge response function of
correlated materials: They lead to depolarization effects for localised
excitations and couple spectra from different Brillouin zones.
