$objectManager = MagentoFrameworkAppObjectManager::getInstance();

        $customerFactory = $objectManager->create('MagentoCustomerModelCustomerFactory');


        $customer = $objectManager->create('MagentoCustomerModelCustomer')->setWebsiteId(1)->loadByEmail('customrr@custom.com');


        try {
            if(!empty($customer->getData('email')))
            {
                $customer->setAttr1(1); // Attr1 = Name of the custom Attribute
                $customer->setAttr2(2); // Attr2 = Name of the custom Attribute
            }
            else
            {
                $customer = $customerFactory->create()->setWebsiteId(1);
            }


            $customer->setLastname("Lastname");

            $customer->setFirstname("Firsty");

            .....

            $customer->save();

$customer->setCustomAttribute('Attr1','value');