Aurelia-slickgrid case insensitive search odata api

I am trying to search Names using column search bar in aurelia slickgrid. This works with backend odata api

d/Customers?$count=true&$filter=(IsActive%20eq%20true%20and%20contains(Name,%20%27So%27))

But when i try to search small cased letters, it does not respond anything.

d/Customers?$count=true&$filter=(IsActive%20eq%20true%20and%20contains(Name,%20%27so%27))

Is there something i can do from aurelia-slickgrid to fix this? I also tried using this but i think backend complains that it does not have substring in filter.

$filter=(substringof('fol', Name))

My column looks like

this.customerColumnDefinition =
        [
            { 
                id: "Name", name: "Name", field: "Name", sortable: true, type: FieldType.string, filterable: true, minWidth: 100,
                onCellClick: (e: Event, args: OnEventArgs): void => { this.router.navigateToRoute("customer", { businessUnitId: args.dataContext.Id }); }
            },