In this paper, we consider the problem of waveform design for a multiple-input multiple-output over-the-horizon (MIMO-OTH) radar system corrupted by colored Gaussian noise and signal dependent clutter. The discrete prolate spheroidal (DPS) sequences are applied to construct the waveforms as their band-limited property is suitable for addressing the operational frequency limitations of the MIMO-OTH radar. Optimum waveforms (possibly nonorthogonal) are designed to maximize the target detection performance of the MIMO-OTH radar system under the constraint of fixed total transmitted energy. The effects of the spatial and temporal correlation of the noise are analyzed. (6 pages)