HI,
based on your requirements, that you want an expertise to connecting 4 tables in sharepoint list and create search control box that will be filtering across all tables.
can you specify how many parameter did you need ? or only one text input ?
i can help you to achieve this. my last project at least using more than 10 tables with different sources (SQL Server, Sharepoint, Excel Online, SAP)
for your consideration, i have enclosed some project on my portofolio called "PP Monitoring", this project will be ensure end to end process balance demand and supplies of truck unit (sales funnel, forecast unit, purchase from principles, delivery monitoring, assempling & production, billing & invoice untuk unit handover to customer).
lets discuss further for better insight of your requirements.
Thanks and have a nice day.