Search Account Record - Where Clause based on custom field

[dodom2]

Hi All,
Am new to EspoCRM and am actually trying to search a record via the API using a where clause on a custom field.
I used the espoCRM client downloaded on github to send this request to the server: $invoice = $client->request('GET', 'Account', ["where" => [["opencartRecordID" => 252]]]);
which generates this link: api/v1/Account?where[0][opencartRecordID]=252
But this request is not working as the server keeps retuning 200 records.
Please can you help highlight what am doing wrong.
Thanks,

[eymen.elkum]

you can easily use the browser's network tool, to catch the link that represents the request of the filtered list