If you want a decent upgrade, you'd need to replace mobo+CPU+ram+GPU.
PCPartPicker part list / Price breakdown by merchant
CPU: Intel - Core i5-8400 2.8GHz 6-Core Processor ($178.99 @ Amazon)
Motherboard: Gigabyte - B360M DS3H Micro ATX LGA1151 Motherboard ($65.99 @ SuperBiiz)
Memory...