Hello Daud,
you should be able to define multiple DHCP pools on IOS based LAN switches as it happens on routers.
see for example
http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_55_se/configuration/guide/swdhcp82.html#wp1098426
In any case if you use an external DHCP server, it can serve IP addresses for different pools on multiple IP subnets you don't need a dedicated DHCP server per client IP subnet,
DHCP relay agent requires the use of ip helper-address on the switch SVIs associated to the client Vlans.
Actually this means converting the non routable client originated DHCP request ( that has a broadcast 255.255.255.255 destnation that is not routable) to a routable packet with IP destination = remote DHCP server address.
Within the packet a field is filled with the IP address of the SVI that received the original request.
This info is used by the DHCP server as a search key to find a free address in the appropriate DHCP pool.
The DHCP offer reply is sent back to the DHCP relay agent that sends it out the SVI facing the client.
Hope to help
Giuseppe