Pcie x16 slot into multiple x4 slots

1 x PCI Express x16 slot, supporting PCIe and running at x16 * The PCIEX16 slot shares bandwidth with the M2C_CPU connector

So, to answer your original question, if you're happy to abandon any other PCI devices you currently have, you can choose a motherboard with more PCIe x1 slots;

pciex1 slot IPCIE16XD11 is Multiple SFF-8654 x4 to PCIe x16 Slot Expansion with Broadcom MegaRAID 9560-16i, 9560-8i, 9580-8i8e, 9500-16i, 9500-8i,

pciex16 slot A PCIe x8 card will fit in any PCIe x8 or PCIe x16 slot PCIe cards larger than the PCIe slot may fit in the smaller slot but only if it is open