partner-contact/partner_sector/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- © 2015 Antiun Ingenieria S.L. - Javier Iniesta
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

    <record model="ir.ui.view" id="view_partner_form_sector">
        <field name="name">Partner form with sector</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="arch" type="xml">
            <field name="phone" position="before">
                <field name="sector_id" placeholder="Sector"
                       options='{"no_open": True}'
                       attrs="{'invisible': [('is_company', '=', False)]}"/>
                <field name="secondary_sector_ids" widget="many2many_tags"
                       attrs="{'invisible': [('is_company', '=', False)]}"/>
            </field>
        </field>
    </record>

    <record model="ir.ui.view" id="view_partner_tree_sector">
        <field name="name">Partner tree with sector</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_tree"/>
        <field name="arch" type="xml">
            <field name="email" position="after">
                <field name="sector_id"
                       attrs="{'invisible': [('is_company', '=', False)]}"/>
            </field>
        </field>
    </record>

    <record model="ir.ui.view" id="view_res_partner_filter_sector">
        <field name="name">Partner search with sector</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_res_partner_filter"/>
        <field name="arch" type="xml">
            <field name="category_id" position="after">
                <field name="sector_id"
                       string="Sector"
                       filter_domain="['|',('sector_id','ilike',self),
                                           ('secondary_sector_ids','ilike',self)]"/>
            </field>
            <filter name="salesperson" position="after">
                <filter name="sector"
                        string="Sector"
                        domain="[('is_company','=', True)]"
                        context="{'group_by': 'sector_id'}"/>
            </filter>
        </field>
    </record>

</odoo>