D3-brane - D-instanton configuration and N=4 super YM theory in constant self-dual background

We consider SO(4) x SO(6) invariant type IIB string solution describing D3-branes superposed with D-instantons homogeneously distributed over D3-brane world-volume. In the near D3-brane horizon limit this background interpolates between AdS_5 x S^5 space in UV and flat space (with non-constant dilaton and RR scalar) in IR. Generalizing the AdS/CFT conjecture we suggest that type IIB string in this geometry is dual to N=4 SYM theory in a state with a constant self-dual gauge field background. The semiclassical string representation for the Wilson factor implies confinement with effective string tension depending on constant D-instanton density parameter. This provides a simple example of type IIB string -- gauge theory duality with clear D-brane and gauge theory interpretation.