  We present broad-band pulsation and spectral characteristics of the accreting
X-ray pulsar OAO 1657--415 with a 2.2 d long \emph{Suzaku} observation carried
out covering its orbital phase range $\sim$ 0.12--0.34, with respect to the
mid-eclipse. During the last third of the observation, the X-ray count rate in
both the X-ray Imaging Spectrometer (XIS) and the HXD-PIN instruments increased
by a factor of more than 10. During this observation, the hardness ratio also
changed by a factor of more than 5, uncorrelated with the intensity variations.
In two segments of the observation, lasting for $\sim$ 30--50 ks, the hardness
ratio is very high. In these segments, the spectrum shows a large absorption
column density and correspondingly large equivalent widths of the iron
fluorescence lines. We found no conclusive evidence for the presence of a
cyclotron line in the broad-band X-ray spectrum with \emph{Suzaku}. The pulse
profile, especially in the XIS energy band shows evolution with time but not so
with energy. We discuss the nature of the intensity variations, and variations
of the absorption column density and emission lines during the duration of the
observation as would be expected due to a clumpy stellar wind of the supergiant
companion star. These results indicate that OAO 1657--415 has characteristics
intermediate to the normal supergiant systems and the systems that show fast
X-ray transient phenomena.
