to increase the number of open partitions to 100.000 (just an example, increase depends on your env)
exec sp_configure "number of open partitions", 100000
you might want to check other config options as well:
exec sp_monitorconfig "all"
especially check parameters:
number of open objects
number of open indexes
if needed, increase in the same using sp_configure
increasing these config options is dynamic, no server restart needed
extra memory is required for these options, you might need to increase max memory as well
to see how much memory is still available:
exec sp_configure memory