  We scrutinize the impact of various relevant scalar leptoquarks on the
physical observables associated with the rare semileptonic decay processes of
$B_s$ meson involving $b \to (u, c) l\bar \nu_l$ quark level transitions. We
constrain the new parameter space consistent with the experimental limit on
Br($B_{u,c} \to \tau \nu_l$), Br($B \to \pi \tau \bar \nu_\tau$), $R_{D^{(*)}},
R_{J/\psi}$ and $R_\pi^l$ observables. Using the allowed parameter space, we
compute the branching ratios, forward-backward asymmetries, lepton and hardon
polarization asymmetries of $B_s \to (K^{(*)}, D_s^{(*)}) \tau \bar \nu_\tau$
decay modes. Forbye, we look at the possibility of existence of lepton
non-universality in these processes.
